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Filar Micrometer
A filar micrometer is a specialized eyepiece used in astronomical telescopes for astrometry measurements, in microscopes for specimen measurements, and in alignment and surveying telescopes for measuring angles and distances on nearby objects. "Filar" derives from the Latin ("thread"). It refers to the fine threads or wires used in the device. Construction and use A typical filar micrometer consists of a reticle that has two fine parallel wires or threads that can be moved by the observer using a micrometer screw mechanism. The wires are placed in the focal image plane of the eyepiece so they remain sharply superimposed over the object under observation, while the micrometer motion moves the wires across the focal plane. Other designs employ a fixed reticle, against which one wire or a second reticle moves. By rotating the eyepiece assembly in the eyetube, the measurement axis can be aligned to match the orientation of the two points of observation. At one time, it was co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ladd Observatory Micrometer
Ladd or Ladds may refer to: People *Ladd (surname) *Brent Ladds (born 1951), Canadian ice hockey administrator *Ladd McConkey (born 2001), American football player Places ;In the United States *Ladds, Georgia, an unincorporated community *Ladd, Illinois, village *Ladd, Missouri, an unincorporated community *Ladd, Virginia, village Other *Ladd's Addition, a neighborhood of Portland, Oregon, United States *Ladd Arboretum, arboretum in Evanston, Illinois, United States *Ladd Army Airfield, military airfield at Fort Jonathan Wainwright, Fairbanks, Alaska, United States *LADD Furniture, now part of La-Z-Boy *Ladd Observatory, astronomical observatory of Brown University, Providence, Rhode Island, United States * Ladd Peak, a mountain in Wyoming * Ladd's cordials, soft drink company in Adelaide, South Australia *The Ladd Company The Ladd Company was an American film production company founded by Alan Ladd Jr., Jay Kanter, and Gareth Wigan on August 18, 1979. In 1979, the three f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pixels
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest addressable element in a dot matrix display device. In most digital display devices, pixels are the smallest element that can be manipulated through software. Each pixel is a sample of an original image; more samples typically provide more accurate representations of the original. The intensity of each pixel is variable. In color imaging systems, a color is typically represented by three or four component intensities such as red, green, and blue, or cyan, magenta, yellow, and black. In some contexts (such as descriptions of camera sensors), ''pixel'' refers to a single scalar element of a multi-component representation (called a ''photosite'' in the camera sensor context, although ''sensel'' is sometimes used), while in yet other contexts (like MRI) it may refer to a set of component intensities for a spatial position. Software on ear ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surveying Instruments
Instruments used in surveying include: * Alidade * Alidade table * Cosmolabe * Dioptra * Dumpy level * Engineer's chain * Geodimeter * Graphometer * Groma (surveying) * Laser scanning * Level * Level staff * Measuring tape * Plane table * Pole (surveying) * Prism (surveying) (corner cube retroreflector) * Prismatic compass (angle measurement) * Ramsden surveying instruments * Ranging rod * Surveyor's chain * Surveyor's compass * Tachymeter (surveying) * Tape (surveying) * Tellurometer * Theodolite ** Half theodolite ** Plain theodolite ** Simple theodolite ** Great theodolite ** Non-transit theodolite ** Transit theodolite ** Seconds theodolite ** Electronic theodolite ** Mining theodolite ** Suspension theodolite ** Traveling theodolite ** Pibal theodolite ** Registering theodolite ** Gyro-theodolite ** Construction theodolite ** Photo-theodolite ** Robotic theodolite ** Vernier theodolite * Total station * Transit (surveying) * Tripod (surveying ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific Instruments
A scientific instrument is a device or tool used for scientific purposes, including the study of both natural phenomena and theoretical research. History Historically, the definition of a scientific instrument has varied, based on usage, laws, and historical time period. Before the mid-nineteenth century such tools were referred to as "natural philosophical" or "philosophical" apparatus and instruments, and older tools from antiquity to the Middle Ages (such as the astrolabe and pendulum clock) defy a more modern definition of "a tool developed to investigate nature qualitatively or quantitatively." Scientific instruments were made by instrument makers living near a center of learning or research, such as a university or research laboratory. Instrument makers designed, constructed, and refined instruments for purposes, but if demand was sufficient, an instrument would go into production as a commercial product. In a description of the use of the eudiometer by Jan Ingenhousz to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astronomical Instruments
An astronomical instrument is a device for observing, measuring or recording astronomical data. They are used in the scientific field of astronomy, a natural science that studies celestial objects and the phenomena that occur in the cosmos, with the object of explaining their origin and evolution over time. Many are also used in navigation and surveying. Astronomical instruments include:Descriptions here are taken automatically from the linked articles or from items on Wikidata. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Radio plate * * * * * * * * * * * * * See also *Astronomy * Outline of astronomy *Surveying instrument Instruments used in surveying include: * Alidade * Alidade table * Cosmolabe * Dioptra * Dumpy level * Engineer's chain * Geodimeter * Graphometer * Groma (surveying) * Laser scanning * Level * Level staff * Measuring tape * Plane table * ... * Measurement instrument Notes {{DEFAULTSORT:Astronomical instruments ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Measuring Instruments
Instrumentation is a collective term for measuring instruments, used for indicating, measuring, and recording physical quantities. It is also a field of study about the art and science about making measurement instruments, involving the related areas of metrology, automation, and control theory. The term has its origins in the art and science of scientific instrument-making. Instrumentation can refer to devices as simple as direct-reading thermometers, or as complex as multi-sensor components of industrial control systems. Instruments can be found in laboratories, refineries, factories and vehicles, as well as in everyday household use (e.g., smoke detectors and thermostats). Measurement parameters Instrumentation is used to measure many parameters (physical values), including: *Pressure, either differential or static * Flow *Temperature * Levels of liquids, etc. *Moisture or humidity *Density *Viscosity * ionising radiation *Frequency * Current *Voltage *Inductance *C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Christiaan Huygens
Christiaan Huygens, Halen, Lord of Zeelhem, ( , ; ; also spelled Huyghens; ; 14 April 1629 – 8 July 1695) was a Dutch mathematician, physicist, engineer, astronomer, and inventor who is regarded as a key figure in the Scientific Revolution. In physics, Huygens made seminal contributions to optics and mechanics, while as an astronomer he studied the rings of Saturn and discovered its largest moon, Titan (moon), Titan. As an engineer and inventor, he improved the design of telescopes and invented the pendulum clock, the most accurate timekeeper for almost 300 years. A talented mathematician and physicist, his works contain the first idealization of a physical problem by a set of Mathematical model, mathematical parameters, and the first mathematical and mechanistic explanation of an unobservable physical phenomenon.Dijksterhuis, F.J. (2008) Stevin, Huygens and the Dutch republic. ''Nieuw archief voor wiskunde'', ''5'', pp. 100–10/ref> Huygens first identified the correct la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Triangle
A triangle is a polygon with three corners and three sides, one of the basic shapes in geometry. The corners, also called ''vertices'', are zero-dimensional points while the sides connecting them, also called ''edges'', are one-dimensional line segments. A triangle has three internal angles, each one bounded by a pair of adjacent edges; the sum of angles of a triangle always equals a straight angle (180 degrees or π radians). The triangle is a plane figure and its interior is a planar region. Sometimes an arbitrary edge is chosen to be the ''base'', in which case the opposite vertex is called the ''apex''; the shortest segment between the base and apex is the ''height''. The area of a triangle equals one-half the product of height and base length. In Euclidean geometry, any two points determine a unique line segment situated within a unique straight line, and any three points that do not all lie on the same straight line determine a unique triangle situated w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
William Gascoigne (scientist)
William Gascoigne (1612 – 2 July 1644) was an English astronomer, mathematician and maker of scientific instruments from Middleton, Leeds who invented the micrometer and the telescopic sight. He was one of a group of astronomers in the north of England who followed the astronomy of Johannes Kepler, which included Jeremiah Horrocks and William Crabtree. Life and work Gascoigne was born in Middleton, Leeds in 1612, the son of a minor country gentleman. His father was Henry Gascoigne, Esq., of Thorpe-on-the-Hill in the parish of Rothwell, near Leeds, Yorkshire. His mother was Margaret Jane, daughter of William Cartwright. Little is known of his early life. He claimed he was educated at the University of Oxford, although no record of this has been found. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Telecentricity
A telecentric lens is a special optical lens (often an objective lens or a camera lens) that has its entrance or exit pupil, or both, at infinity. The size of images produced by a telecentric lens is insensitive to either the distance between an object being imaged and the lens, or the distance between the image plane and the lens, or both, and such an optical property is called ''telecentricity''. Telecentric lenses are used for precision optical two-dimensional measurements, reproduction (e.g., photolithography), and other applications that are sensitive to the image magnification or the angle of incidence of light. The simplest way to make a lens telecentric is to put the aperture stop at one of the lens's focal points. This allows only rays including the chief rays (light rays that pass through the center of the aperture stop), that will be about parallel to the optical axis on the other side of the lens, to pass the optical system for any object point in the field of view. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrometry
Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other Astronomical object, celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. History The history of astrometry is linked to the history of star catalogues, which gave astronomers reference points for objects in the sky so they could track their movements. This can be dated back to the ancient Greek astronomer Hipparchus, who around 190 BC used the catalogue of his predecessors Timocharis and Aristillus to discover Earth's precession. In doing so, he also developed the brightness scale still in use today. Hipparchus compiled a catalogue with at least 850 stars and their positions. Hipparchus's successor, Ptolemy, included a catalogue of 1,022 stars in his work the ''Almagest'', giving their location, coordinates, and brightness. In the 10th century, the Iranian astronomer Abd al-Rahman al-Sufi carried ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angular Distance
Angular distance or angular separation is the measure of the angle between the orientation (geometry), orientation of two straight lines, ray (geometry), rays, or vector (geometry), vectors in three-dimensional space, or the central angle subtended by the radius, radii through two points on a sphere. When the rays are Line of sight, lines of sight from an observer to two points in space, it is known as the apparent distance or apparent separation. Angular distance appears in mathematics (in particular geometry and trigonometry) and all natural sciences (e.g., kinematics, astronomy, and geophysics). In the classical mechanics of rotating objects, it appears alongside angular velocity, angular acceleration, angular momentum, moment of inertia and torque. Use The term ''angular distance'' (or ''separation'') is technically synonymous with ''angle'' itself, but is meant to suggest the linear distance between objects (for instance, a pair of stars observed from Earth). Measurement Sin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
